The present disclosure relates generally to waste water treatment and, more particularly, to systems and methods for removing solid particulates from waste water allowing for water recovery and re-use.
At least some known boiler systems include bottom ash systems that use water to cool and transport bottom ash from the boiler to an ash pond for disposal. Generally, bottom ash is the non-combustible coal residue from burned fuel. In at least some such systems, the water used to transport the ash is delivered contaminated with solids to the ash pond where the solids are allowed to settle and accumulate. Water is also used in at least some known boiler systems to carry pyrites, economizer ash, and reacted air pollution control reagents used for removal of sulfur from flue gases. Solid particulates are collected in filters that are periodically backwashed to clean out the accumulated filtered material. In at least some known systems, the backwash and filtered materials are typically released to a settling pond as waste sludge. When such waste sludge is accumulated and stored in ash ponds, the potentially toxic constituents may be released by the pond water into the bottom soil and pond run-off. Particulates in the environment or other waste streams may mix and combine with it, making the waste sludge non-suitable for reuse.
Known bottom ash dewatering systems are time-consuming, generally take between four to six hours to handle customary solids, and typically rely on gravity to separate particulates from water. In an effort to speed up the process, at least some facilities use additional separation equipment, such as but not limited to hydro-cyclones. However, the use of such equipment may be limited depending on the characteristics of the waste water.